1. Field of the Invention
This invention relates to pressure vessels and, in particular, to closures for pressure vessels. Pressure vessels of different sizes and strengths depending on the amounts treated therein and on the pressures utilized during process, are utilized in the chemical and other process technology industries in a variety of applications. Accordingly, the closures for such process vessels must be adapted to satisfy a variety of conditions.
2. Description of Prior Art
Closures for pressure vessels having a collar which can be connected to the pressure vessel and a cap, a seal disposed in the area where the cap and the collar contact each other, and a plurality of clamping elements for generating a surface pressure between the collar and the cap are known. These known closures are mostly relatively complicated welded structures which, although they have been dimensioned and calculated beforehand, must later on be checked during extensive tests, even though the type per se has been accepted. In addition, closures of this type require long processing times which result in high manufacturing costs.
In most cases, the caps of such closures, if they are pivotably hinged on the collar, are provided with a hinge mounted on welded-on brackets, which, when the cap is opened, hit the wall of the vessel, which may lead to deformations.
The clamping elements by which the cap is pushed closed, usually are lever systems which are fixed in place, welded on the collar and pivotably attached and are expensive and cannot be changed. The number of the clamping elements cannot be changed, even if the cap is exchanged. In most cases, the entire closure must be replaced, provided this is possible at all.